讲座信息
讲座题目：Midlatitude nighttime plasma depletions over the African-European region: 2014 versus 2019 Swarm plasma density measurements
讲座嘉宾：Zama Katamzi‑Joseph（南非空间局）
讲座主持人：姜国英（中国科学院国家空间科学中心）
时间：3月8日10点
地点：线上 腾讯会议 411-8560-2478 (点此入会）
讲座摘要
Plasma depletions are observed in F-region and topside ionosonde in the nighttime at low and sub-auroral latitudes. These depletions represent significant abrupt changes in background plasma variations. The plasma depletions at low latitudes are known as equatorial plasma bubbles (EPBs), while those at sub-auroral latitudes are known as midlatitude /main ionospheric trough (MIT). However, a few studies have reported on the existence of plasma depletions in the midlatitudes, north of the EPBs zone but south of the MIT zone, particularly during geomagnetic storms. These depletions have been interpreted as evidence of EPB extension to midlatitude regions, however there is some questions on the credibility of this interpretation since these midlatitude depletions are observed in the absence of EPBs. In this study we conducted a statistical analysis of midlatitude nighttime plasma depletions using Swarm plasma density measurements over the African-European longitudes during 2014 (solar maximum) and 2019 (solar minimum). We compared their characteristics in terms of spatial and temporal distributions to those of EPBs and medium-scale traveling ionospheric disturbances (MSTIDs). Result revealed that the midlatitude plasma depletions are anti-correlated to solar and magnetic activities. In addition, these depletions were dominant during the solstices and March equinox, as well as during postmidnight hours. Based on these trends, we concluded that the depletions are most likely related to MSTIDs than EPBs, since most of their distribution trends match (i.e. solar and magnetic activity and season).
嘉宾介绍
| Dr Zama Katamzi-Joseph is a space physics researcher at the South African National Space Agency (SANSA) and a research associate at Rhodes University, South Africa. She completed her undergraduate training in Physics at the University of Cape Town in 2004 after which she joined the National Astrophysics and Space Science Programme for BSc Honours and MSc training. After completing her MSc with distinction at Rhodes University in 2007, she went on to do her PhD at the University of Bath, UK, and graduated in 2011. Her main research topics include ionospheric dynamics and electrodynamics, thermosphere-ionosphere coupling, space weather, ionospheric perturbations, such as at traveling ionospheric disturbances (TIDs) and plasma bubbles. |
